The present invention relates to a method for removing organic contamination from soils, involving the use of a certain surfactant-containing composition to facilitate the removal.
Removal of organic contaminants or pollutants from soil is of great concern. Conventional pump-and-treat remediation, however, has met with limited success, often due to the presence of residual saturated domains of contaminant or strong sorption of the contaminant onto soil components.
Surfactants have been employed in an attempt to enhance subsurface remediation. A review of such techniques has been published by Sabatini et al., "Emerging Technologies in Surfactant-Enhanced Subsurface Remediation," ACS Symposium Series 594, Surfactant-Enhanced Subsurface Remediation, 1995, pages 1-6.
Details of surfactant selection for such use, especially for removal of chlorinated organic contaminants, has been published by Shiau et al., "Surfactant Selection for Optimizing Surfactant-Enhanced Subsurface Remediation," pages 65-79 of the aforementioned ACS Symposium Series 594. This reference discloses that surfactants can improve subsurface remediation by solubilization (increasing the aqueous concentration of the contaminant by partitioning into surfactant micelles) or microemulsification (formation of a middle phase microemulsion with concomitant ultra-low interfacial tensions.) The high performance surfactants which were utilized are alkyl diphenyloxide disulfonates from the DOWFAX.TM. series, ranging from 10 to sixteen carbons in the alkyl group. Surfactant type (structure) is disclosed to be critical to achieving microemulsification systems, unlike solubilization systems where enhancement is relatively independent of surfactant type. Advantages of the DOWFAX.TM. surfactants include their resistance to precipitation in the presence of calcium ion and minimal susceptibility to sorption losses. Reference to this article can be made for detailed information relative to the theory and practice of various types of micellar and middle-phase systems involving surfactants, useful concentrations, their preparations, and their relative advantages.
A variety of surfactants are known for industrial and other applications. U.S. Pat. No. 4,664,834, Forsberg, May 12, 1987, discloses a water-dispersible reaction product of (A) at least one compound represented by the formula ##STR1## herein R is a hydrocarbyl group of from about 8 to about 40 carbon atoms, with (B) at least one water-dispersible amine terminated poly(oxyalkylene). Aqueous concentrates and water-based functional fluid comprising these compositions are also disclosed. These reaction products are useful as shear-stable thickeners for such functional fluids.